Because of a general difference in the electrical potentials between a metallic product and a roller-conveyor roll, electrical currents and spark formation can result in surface defects in the manufactured material.
It is known (DE 24 26 135 C2) to provide a roller conveyor roll for the transport of rolled products such as rolling mill products which can resist impact with the rolled product. It has not been noted therein that such roller conveyor rolls also contribute to electrical currents and spark formation which can degrade the rolled product.